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whirly 03-30-2009 09:49 AM

Basement Wiring Questions
This is for those Licensed Electricians out there ...

I am currently wiring my basement and i have a few of questions that i cant seem to find the answer for ...

1) I am running 12/2 wire for all my basement receptacles (I know ... Overkill but i would rather have more then less) So, my question is ... Can i use standard 15 Amp receptacles or do i have to use 20 Amp based on the wire size?

2) What is the maximum amount of Junction boxes you can use on any one Circuit? What is the trade consensus on Junction Boxes.

3) I have used 240v Square/Deep boxes as Junction, I know the limit on the Octagon box is 6 wires, excluding ground ... Is there a different limit for these bigger boxes? If there is, what is the maximum amount of wires you would tie together?

4) The general rule is 14 devices on a 12/2 wire, I know that this is based loosely on what you might push through the receptacles ... but what is the realistic number you would use?

Thanks in advance Guys !

HouseHelper 03-30-2009 10:37 AM

1. The 15A are fine as long as there is more than one (a duplex is two)
2. Fewer is better, but there is no limit.
3. No such thing as a "240v Square/Deep" box. Max number of wires depends on the box dimensions. Plastic boxes will have the total volume and number or wires stamped inside.
4. General rule yes, but for a dwelling in the US, there is no set limit. For general purpose receptacles, I usually go for 18-20.

Bob Mariani 03-30-2009 10:41 AM

1) yes... 15 amp outlets are used even if you have a 20 amp circuit

2) No maximum. 3 watts per sq foot is used to determine the power needed for a specified area. Number of boxes does not mean you are going to use more power at one time.

3) Not sure what a 240V sq box is. they make 4 11/16 and 4" sq boxes but you also need to know the depth of the box and the depth of the plaster ring. For typical 21 cu. in outlet boxes use only 3 pair of 12/2 cables. Number of wires spliced together is not any issue. Number of boxes and size of boxes are.. but need more details to help with this. Go to the library and look at the charts which give your this wire fill.

4) No such rule... makes no sense at all.

whirly 03-30-2009 10:59 AM

It is in fact a 4" square box, 2-1/8th deep

jbfan 03-30-2009 11:08 AM

Why do you want to use j-boxes? It would be easier to wire from panel, then to each device box until the end.
You know that any j-box must remain assessable.
The local building department may have a limit on the number of outlets allowed on each circuit.
My area allows 10 only.

whirly 03-30-2009 11:22 AM

I am using J boxes where i have the same circuit, going to two distinct locations in opposite directions in the basement. In addition, I may be switching one run and not another ....

I wanted to limit the number of cables back into the panel to the cct breaker.

Am i off base ?

Please feel free to criticize, Speak freely.

jbfan 03-30-2009 11:30 AM

You still need to have the same number of cables at the panel to achive what you are trying to do in the basement.
What all electricians do is run the homerun cable to the first device,(recept,switch), then feed to the next one, then the next and so on. The only junctions are in the device boxes and no extra splices around.

Read a black and decker book on wireing and see how they show you to run your circuits.

Bob Mariani 03-30-2009 12:31 PM

You could use one 4" deep box with a 1/2" one or two gang raised plaster ring and use this as your one and only one junction box. Run a 12/3 to this box. Then run two 12/2 wires out of it to start a semi-circle loop of wiring to outlets and switches. one 12/2 in one 12/2 out of each one until you get to the end. then 12/2 out of the switch to the lights. Maybe another 12/2 to feed a TV and speaker system if you have one. Or if you have any appliances or a computer/gaming station run a separate 12/2 to that area. But 12/3 is costly and may be cheaper to run separate 12/2 cables.

theatretch85 03-30-2009 12:52 PM

Just as an FYI, I bought a 250' spool of 14/3 (yeah I know, not 12/3) this last weekend and that was only about $38 dollars at Home Depot. 12/3 shouldn't be that much more expensive to run.

12/2 is NOT overkill for outlets; in fact I would run nothing less to any outlet circuits, gives you plenty of options for circuit use in the future. Also is nice that you shouldn't have to worry too much about what outlet you plug your vacuum or space heater into.

J-boxes must always be kept accesible, so keep that in mind when considering installing a j-box. Sometimes its just better to bring the power feed into the first closest box and branch off from there even if it means a little more wire to be used to run the other direction. This would eliminate the need for the J-box as the outlet or switch you run it to would still remain accesible.

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